Hydraulic interlock mechanism on back hoe



Nov. 1, 1966 E. M. PARSEN 3,232,452

HYDRAULIC INTERLOCK MECHANISM ON BACK HOE Filed May 22, 1964 5 Sheets-Sheet l Edward M. Parsen 1N VEN TOR.

Nov. 1, 1966 E. M PARSEN 3,282,452

HYDRAULIC INTERLOCK MECHANISM ON BACK HOE Filed May 22, 1964 5 Sheets-Sheet 2 Fig.2

E dwara' M. Parsen INVENTOR.

Nov. 1, I966 E- M. PARSEN 3,232,452

HYDRAULIC INTERLOCK MECHANISM ON BACK HOE Filed May 22, 1964 5 Sheets-Sheet 5 Fig. 4 A0 Edward M Parse/I INVENTOR.

3,282,452 HYDRAULIC INTERLOCK MECHANISM ON BACK HOE Edward M. Parsen, Box 123, Miller, S. Dak. Filed May 22, 1964, Ser. No. 369,479 Claims. (Cl. 214-138) This invention comprises a novel and useful hydraulic interlock mechanism and constitutes an improvement over and comprises a continuation-in-part of my prior application Serial No. 90,142,. filed February 17, 1961, for Boom Loading Devices, now Patent No. 3,134, 92 of May 26, 1964.

In my prior patent there is disclosed and claimed a chassis as of a motorized vehicle upon the rear end of which is mounted a boom assembly carrying an implement such as a back hoe or the like together with means for effecting a vertical lifting and lowering of the boom between an elevated stored or loading position in which the boom assembly overlies and rests upon and is carried by the chassis in a compact manner improving the roadability of the device or is lowered to a downwardly extending position in which the boom assembly and the back hoe carried thereby perform all of the normal functions of the power operated back hoe.

During the operation of the device as disclosed and claimed in my prior patent, it has been found that as the boom is being raised or lowered between its operative position and its loaded positions, and further while the boom is in its loaded or elevated position, there is a tendency for the boom assembly to turn, move or drift about its vertical axis of movement. Obviously, such movement is undesirable and may often constitute a serious danger. It is therefore necessary to afford some means for locking the boom assembly against horizontal swinging about a vertical axis when the boom is in or is being moved to or from its loaded position upon the motorized chassis.

It is therefore the primary purpose of the invention to eliminate the danger resulting from human failure to physically lock the turntable before loading by providing a locking mechanism for positively preventing horizontal swinging of the boom assembly about its vertical axis of movement during the loading or unloading operation and to insure that the turntable will stay locked at all times during transport or storage for example, when the vertical axis of movement is laid horizontally or parallel to the side members of said chassis.

A further object of the invention is to provide an operating mechanism for lifting and lowering the boom between a lowered operative position and an elevated, loaded and inoperative position and which operating mechanism shall include means for positively locking the boom assembly against horizontal swinging movement about a vertical axis when the boom is elevated from its operative position or is in a loaded position upon the chassis.

A further object of the invention is to provide a hydraulic actuating mechanism in accordance with the preceding objects which shall include a hydraulic interlock means operable as a part of the loading or unloading operation of the boom assembly to lock the boom against horizontal swinging movement on the vertical axis during the loading or unloading operation.

A still further object of the invention is to provide a hydraulic interlocking mechanism which upon initiation of its operation is effected to first lock the boom assembly against horizontal swinging movement about a vertical axis and after this interlock has been completed is then effective to lift or lower the boom assembly selectively to its loaded or unloaded positions and maintain United States Patent 6 ice the turntable locked until the unit is unloaded to working position.

A still further and more general purpose of this invention is to provide a hydraulic actuating system which shall encompass within its scope the performance of two separate hydraulic operations in sequentially timed relation with means preventing operation of the second operation until the first operation has been completed.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a view in side elevation of a portion of a motorized chassis upon the rear end of which is mounted by means of a support means and turntable a boom assembly carrying an apparatus such as a back hoe or other earth excavating implement and to which the novel hydraulic interlock mechanism of this invention has been applied with the boom assembly being shown in full lines in its operative or unloaded position and being shown in dotted lines between its unloaded and loaded positions;

FIGURE 2 is a top plan view of the arrangement of FIGURE 1 with the boom assembly being shown in its lowered, unloaded and operative position;

FIGURE 3 is a diagrammatic view of the hydraulic system of this invention with the apparatus being in normal operating condition;

FIGURE 4 is a view similar to FIGURE 3 but with the apparatus being intermediate the operation of lifting and loading the boom assembly upon the vehicle chassis.

FIGURE 5 is a view similar to FIGURE 3 but with the apparatus being intermediate the operation of unloading and lowering from the vehicle chassis to the normal working condition;

FIGURE 6 is a view similar to FIGURE 3 but showing the apparatus at the completion of the unloading operation;

FIGURE 7 is a detail view in vertical section of the turntable lock means including the hydraulic operating means therefor;

FIGURE 8 is a detail view of a resilient detent means constituting a part of the turntable lock means; and

FIGURE 9 is an elevational view of the reversible control valve in its normal neutral position.

In the accompanying drawings, the numeral 10 designates generally a portion of a motorized chassis such as a truck or other vehicle having the usual side frame members 12 and upon the rear end of which is mounted a boom assembly indicated generally by the numeral 14. Although the boom assembly may be intended for various purposes, it is illustrated as including a back hoe construction indicated generally by the numeral 16 with the back hoe bucket 18 being pivotally carried by an arm 20 and pivotally operated thereon as by a conventional fluid-pressure operating means 22, and with the arm itself being pivoted as at 24 to the boom 26 and being raised or lowered upon the boom by means of the fluid pressure operated cylinder piston unit 28. Inasmuch as the details of the back hoe or other implement carried by the boom 26 and the operating means therefor constitutes no part of the invention set forth and claimed hereinafter, a further description thereof is deemed to be unnecessary.

However, as in my prior patent, the present invention includes a turntable indicated generally by the numeral 30 and to which the boom assembly 14 is pivotally connected as at 32 for vertical swinging movement about the horizontal transversely extending axis of the pivot 32.

The turntable itself is secured to a support means indicated generally by the numeral 34 so that the turntable is carried by the support means but may swing horizontally about a vertical axis with respect to the sup-port means by a conventional operating mechanism, not shown. The support means itself is connected as by a horizontal pivot means 36 to the chassis in any suitable manner and actuating means in the form of hydraulic fluid cylinder and piston units 44 are connected to the chassis side frame members or any other suitable portion of the chassis and to the support means 34 to effect vertical swinging of the support means, the turntable carried thereon and the boom assembly carried by the turntable about the horizontal transversely extending axis of the pivot means 36. The vertical swinging movement imparted to the support means and the associated structure is sufiicient to enable the assembly to be swung from the lowered, unloaded and operative position of the device shown in full lines in FIGURE 1 past the dotted lineposition to a lifted, inoperative and loaded position, in which loaded position the support means, turntable, boom assembly and the implement 16 carried thereby will be folded back upon the chassis into a compact arrangement for easy transportation as set forth in greater detail in my prior patent.

As so far described, the arrangement and the structure is preferably substantially identical with that set forth in my prior patent.

In accordance with this invention means are provided for selectively locking the turntable against rotation during the period when the boom is to be lifted from its lowered working position, is to be moved to a loaded position or is to be returned from the latter to its working position.

Referring now more particularly to FIGURE 7 it will be seen that the support means 34 and the turntable includes parallel cooperating plates consisting of the support means base plate or bed 42 andthe turntable rotatable plate or bed 44. A pivot pin 46 comprises the pivot by which the turntable 30 is rotatably mounted upon the support means 34 for rotation about the vertical positioning axis extending through thevpivot pin 46.

A lock mechanism is provided for selectively locking the turntable to the support means against rotation about the vertical axis of the pin 46 when the boom assembly is in longitudinal alignment or in the same vertical plane as the longitudinal axis of the chassis. For this purpose, the turntable plate 44 is provided with a locking bore 48 and a locking pin 56 is insertable into or withdraw-able from the bore 48. The locking pin itself is preferably carried by a'locking piston '52 slidably received in the locking hydraulic cylinder 54 to the opposite ends of which hydraulic fluid under pressure is selectively applied by the conduits 56 and 58 respectively. By properly controlling the flow of hydraulic fluid to these conduits, .it is evident that the locking pin may be selectively moved into locking engagement with the turntable plate 44 as shown in FIGURE 7 .to thereby lock the boom assembly and the turntable against rotation for horizontal swinging movement and in longitudinal alignment with the axis or center line of the chassis 10.

In order to effect controlled hydraulic operation of the locking pin and also of the actuating members or cylinders 40, there is provided a hydraulic system which as shown in FIGURES 3 to 6 includes a hydraulic pump 62 or other source of hydraulic fluid under pressure whose intake is connected by conduit 64 to a hydraulic fluid reservoir 66. The discharge or pressure side of the pump 62 is connected by a conduit 68 to a supply conduit '76 comprising fluid pressure inlet of a selector distributing valve 72. The valve 72 includes a pair of passages 74 and 76 therein and has an operating handle 78 which is urged by the springs 80 and 82 to an intermediate and inoperative position as shown in FIGURE 9, and may be manually operated to either of the dotted line positions 4 shown in FIGURES 4 and 5 to eiiect operation of the hydraulic system.

A conduit 84 constitutes a discharge line from the selector valve 72 and the return of the hydraulic fluid pressure to the reservoir 66 for recirculation by the pump. In the conduit 84 there is provided a control valve assembly 85 by which the normal operation of the back hoe or other apparatus is controlled in the usual manner.

A nonreturn check valve 86 is interposed in a by-pass conduit 88, this valve also constituting a pressure relief valve which thus governs and controls the pressure applied to the system by the pump 62.

A pair of flow conduits 90 and 92 are connected to selector valve 72 and to the locking cylinder 54 and the actuating members or loading cylinders 40 of the apparatu-s.

With continuing reference to FIGURES 37 it will be observed that the previously mentioned conduit 58 of the locking cylinder 54 is connected to the conduit 90, which latter is also connected to a combined selector and relay valve indicated generally by the numeral 100.

Branch conduits 102 and 194 respectively connect the two inner ends and the two outer ends of the loading cylinder 40. A further conduit 106 is connected to conduit 104 and the selector valve 190 while the conduit 108 connects the branch conduit 102 with the selector valve. It should be noted that the two conduits 90 and 106 are in diametrically opposite alignment on opposite sides of the selector valve 160, while the conduits 108 and 92 are similarly diametrically aligned but in longitudinally spaced relation to the first mentioned set of conduits as shown for example in FIGURE 6.

Finally, there is provided a conduit 110 connected to conduit 92 and a pair of branch conduits 112 and 114 connecting the conduit 110 to the previously mentioned conduit 56.

Disposed in the branch conduit 112 is a nonreturn check valve 116, while indicated at 118 of the conduit 1 14 is a check valve of the adjustable pressure relief type. The functions of these valves are vital to the operation of the hydraulic system as will beset forth hereinafter.

Referring now to FIGURES 7 and 8 it will be observed that the selector valve 100 consists of a cylindrical casing 120 comprising aliydrau-lic cylinder in which is slidably received the hydraulically operated plunger 122. The plunger comprises a valve member which is releasably retained in different positions of reciprocation as by means of a pair of latch recesses 124 disposed upon the side of the plunger and comprising circumferentially extending grooves therein and with which cooperate a detent ball 126 received in a tubular boss 128 on the cylinder and yieldingly urged as by spring 129 retained by a closure plug 131 against the plunger 122. Thus, as the plunger is shifted longitudinally within the cylinder 12%, it will be releasably and yieldably held in its different positions of adjustment by engagement of the detent ball 126 in the detent recesses 124 of the plunger.

The piston or plunger 122 is provided with a piston rod extending through one end of the hydraulic cylinder 120. The piston itself is provided with a pair of circumferentially extending valve passages or bores 132 and 134 which cooperate with the series of conduits connected to the cylinder. Thus, in one position of adjustment of the valve plunger the passages 132 and 134 will be out of registration with all of the conduits as shown in FIG- URES 3 and 6 thereby blocking intercommunication between the source of fluid pressure as supplied by the conduit 90 and the actuating or loading cylinders 40. This is the position shown in FIGURE 3. However, in the other position of the valve plunger 122, the valve passage 132 shown in FIGURE 4 will be caused to establish communication between the conduits 9t! and 106 thereby connecting through the selector valve the branch conduit 104 and thus one end of the loading cylinders 40 to the control valve 72. When the passage 134 is registered with the conduits 92 and 108 as shown in FIGURE 5, communication with the source is established with the other ends of the loading cylinders through conduit 102. Depending upon which of the conduits 90 or 92 is the pressure supply conduit with the other the exhaust or return conduit, it is evident that with the valve in the positions shown in FIGURES 4 and 5, the loading cylinders 40 will be either expanded or contracted to thus effect the loading or unloading operation of the apparatus by the hydraulic system. As will be noted by a comparison of FIGURES 4 and 5, proper manipulation of the control valve 72 between the dotted line positions of FIGURE 4 and FIG- URE 5 will determine whether the cylinders 40 will load or unload the boom assembly upon the chassis 10.

A vital part of this invention consists of the provision of an automatic interlock mechanism associated with the hydraulic actuating system. For this purpose, referring primarily to FIGURE 7 it will be observed that suitably mounted upon the support means 34 as by a bracket 140 is a lever 142 to which an overcenter spring 144 may be attached to urge this lever into one position or extreme of this movement. The lever is connected to the piston pin 130 in any suitable manner and also is connected between a pair of fingers 146 of the lock pin 50. As a result of this arrangement, the lock pin 50 is interconnected with the selector valve to prevent loading or unloading of the cylinders 40 for loading or unloading the boom assembly upon the chassis except when the lock pin 50 is locking the turntable against horizontal swinging movement about the vertical axis of the pin 46.

The operation of the hydraulic system per se and the apparatus in accordance with this invention is as follows:

FIGURES 3-6 illustrate successive phases of the opera-tion of the hydraulic system and of the apparatus as effected thereby. FIGURE 3 shows the hydraulic system and the associated parts of the apparatus in the normal working position of the apparatus, with a boom assembly lowered, the turntable lock pin retracted so that the boom may be swung both horizontally and vertically during the normal operation, as when the back hoe .18 is being manipulated. It will be noted in this position that the converter valve 72 disconnects the source of power which is the pump 62 from the conduits 90 and 92 which are connected to the turntable lock cylinder 54, the selector valve 100 and the loading or lifting cylinders 40. However, the selector valve 100 has its valve plunger 122 in a position to prevent registration of the ports with the passages through the valve thereby disconnecting the conduits 90 and 92 from the lift cylinder conduits 102 and 104. However, the position of the valve 72 is such, as shown in FIGURE 3, as to prevent circulation of hydraulic fluid from the pump 62.

When it is desired to lift or load the boom assembly upon the vehicle chassis, that is, to move it from the full line position of FIGURE 1, it is first necessary to position the boom assembly in longitudinal alignment with the axis of the vehicle chassis or in the position shown in FIGURE 2. The control valve 72 is then operated by shifting the handle 78 from the neutral position of FIG- URE 9, to which it is yield-ingly urged by the two springs 80 and 82, in a clockwise manner to the right-hand position of its movement as shown in FIGURE 1. This connects the pressure side of the pump 62 to the conduit 90, while the return side of the system has a conduit 84 connected to the conduit 92. In this position, the flow of fluid is from the pump 62, by the conduits 68 and 70 to the valve 72,'by the passage 74 therethrough to the conduit 90,'and thence by the conduit 90 to the selector Valve 100. However, since the valve passages 132 and 134 are out of registration with the associated cylinder conduits 106 and 108 as shown in FIGURE 3, no fluid can reach the lift cylinders at this time. Flu-id pressure, through the branch conduit 58, is then delivered to the hydraulic cylinder 54 of the turntable lock means to thus move the piston 52 and extend the lock pin 50 to the position shown 6 in FIGURE 7, into engagement with the locking bore 48 of the turntable plate 44. Fluid from the other side of piston 52 is exhausted through conduit 56, one-way valve 116, conduits 112, 110 and 92, valve 72 and conduit 84 to reservoir 66. At this time, the turntable is locked against any movement.

When the turntable lock pin is moved to its locking position, the outermost of the fingers 146 on the locking pin will engage and displace the connecting or relay lever 142 from the position shown in FIGURE 3 in a counterclockwise direction about its pivot pin until an overcenter position of the spring 144 is reached, at which time the lever will snap to its other extreme position shown in FIGURES 4, 5 and 7. This in turn will effect a shifting of the selector valve plunger 122 from the inoperative position shown in FIGURE 3 to the operative position shown in FIGURES 4, 5 and 7. At this time, after the locking pin 50 has been moved into locking engagement with the turntable, the pressure conduit as shown in FIGURE 4 is placed in communication by the valve passage 132 with the conduit 106 and by means of the branch conduit 104 applies fluid pressure to the lift cylinders 40 to contract the latter and thus effect an upward tilting or lifting of the support means 34 and the associated turntable and boom assembly therewith. At the same time, the valve passage 134 places the return conduit 92 in communication with the conduit 108 so that the hydraulic fluid in the other end of the fluid or lifting cylinders 40 is returned through the selector valve back to the reservoir of the hydraulic system.

It will thus be seen that upon movement of the manually operated control valve 72, the turntable is first locked against horizontal swinging movement by engaging the lock pin 50 therein and as response to such locking movement, operating fluid is then applied to the loading cylinders to effect lifting and loading of the support means, turntable and boom assembly upon the vehicle chassis. The parts remain in this position during transportation of the device and until such time as is desired to restore the apparatus to its working condition. It will be appreciated that as soon as the loading operation is completed, the control valve handle 78 is released, and the spring means 80, 82 return the valve to its inoperative or neutral position, breaking communication of the conduits 90, 92 with the source of pressure, thus preventing the ingress or escape of fluid from either end of the loading cylinders 40 and thus locking the parts in this position. When it is desired to restore the device to operative working condition, the control valve handle 78 is then moved in a counterclockwise direction to the position shown in FIGURE 5. At this time, it is noted that the valve passages 132, 134 continue to establish communication between the conduits 90, 92 and the conduits 106 and 108 to the lifting cylinders. Consequently, in the position shown in FIGURE 5, pressure fluid from the conduits 68, 70 is routed by the valve passage 74 to the conduit 92 which thus becomes the pressure supply conduit of the system while the conduit 90 functions as the hydraulic fluid return line. From the conduit 92, fluid pressure is delivered through the passage 134 of the selector valve to the conduit 108 and through the conduit 102 to the lift cylinders 40 thereby elongating the latter and moving the support means, turntable and boom assembly to their lowered position.

During this part of the operation, the conduit 110 is likewise supplied with hydraulic fluid under pressure. However, the check valve 116 prevents flow into the conduit 56 through the branch conduit 112 while the adjustable pressure relief check valve 118 similarly prevents flow from the conduit 110 to the conduit 56. Thus, the locking pin 50 remains in its turntable locking position to which it was moved during the initial part of the loading operation described in connection with FIGURE 4.

However, after the lowering and unloading operation has been completed, with the cylinders 40 'being expanded to a maximum length and with the support means, turntable and boom being in their maximum lowered position ready for operation, it is now desired to withdraw the locking pin in order that the normal horizontal swinging movement of the turntable and of the boom assembly may be performed during the normal working of the apparatus. Thus, when the cylinders 40 have reached their maximum elongation, the pump 62 produces a further rise in pressure in the pressure supply conduit 92 which through the conduit 110 is applied to the pressure relief valve 118. This valve then opens at a pressure which is less than that of the safety valve 86 so as to supply this higher pressure fluid through the conduit 56 into the hydraulic actuating cylinder 54 of the locking mechanisms. This in turn forces the locking plunger inwardly of its cylinder, this being permitted by escape of the fluid behind the lock cylinder plunger through the conduits 58 and 90. Accordingly, the locking pin 50 is withdrawn from its engagement with the turntable so that the latter is now free to move. FIGURE 6 shows the position of these parts after the locking pin has been withdrawn. As will be noted, the innermost finger 146 on the locking pin has engaged the lever 142 and moved it in a clockwise direction by'the snap action of the overcenter spring 144,

FIGURE 7, thereby disengaging the selector valve plunger 122 from its position connecting the various ports therethrough. When the control valve handle 78 is then released, the springs again return the valve to its normal neutral position shown in FIGURE 9, and the parts are now again in the position shown in FIGURE 3 in readiness for the next loading operation.

A very important feature of thisinvention resides in .the construction and the operation of the valve 116 and conduit 92 passing upwardly through the conduit 110 is applied against the valve .116 which remains closed. When the pressure reaches sufiicient value to overcome the adjustable pressure relief of one-way valve 118, the latter opens and the pressure fluid is supplied by the conduit 56 in to the hydraulic cylinder 54 to thus cause retraction or unlocking of the locking pin with the turntable, with the fluid on the other side of the plunger in the locking cylinder being vented through the conduit 58 to the return conduit 90.

In addition, the particularoperation of the relay mechanism connecting the locking cylinder 54 with the selector .valve assembly .100 insuresthe, successive or sequential operation of first locking the turntable before the lifting cylinders are contracted on the loading operation while the lifting cylinders are expanded before the locking pin is withdrawn on the unloading operation.

It is to be appreciated that the principles of this invention while particularly adapted for use in hydraulic systems for loading and unloading boom assemblies upon motorized vehicles as specifically set for-11h here-in, are in some respects applicable generally to hydraulic systems where it is desired to effect successive operations of different mechanisms upon operation of the hydraulic system in ,a' first manner, and to effect a reverse sequence of operation of these mechanisms when the hydraulic systems are operated in a reverse manner.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described,

and accordingly all suitable modifications and equivalents ,8 may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A foldable power operated boom construction comprising in combination a vehicle having a chassis,

(a) a boom assembly movable between a loaded, lifted and inoperative position in which it is lifted and folded back over said chassis and an unloaded, lowered and operative position,

(b) a support assembly mounted upon the rear end of said chassis for swinging movement about a horizontal axis extending transversely of said chassis,

(c) actuating means connected to said chassis and to said support assembly for vertically tilting the latter about said horizontal axis,

(d) a turntable pivotally mounted upon said support means for turning about a vertical axis,

(c) said boom assembly being mounted upon and carried by said turntable,

(f) a hydraulically operated lock means for maintaining said turntable fixed against rotation about said vertical axis with said boom assembly disposed in longitudinal alinernen-t with said chassis,

(g) a source of hydraulic fluid under pressure,

(h) a control valve connecting said source to said turntable lock means,

(i) means operable only when said lock means is locking said turn-table for connecting said source to said actuating means and to selectively effect raising and lowering of said support means, turntable and boom assembly.

2. The combination of claiml including means responsive to completion of the lowering and unloading of said boom assembly by said actuating means for effecting release of said lock means from said turntable.

3. The combination of claim 1 wherein said control valve is normally urged to aneutral inoperative position and is manually adjustable selectively to boom loading and boom unloading positions.

4. A foldable power operated boom construction corn prising in combination a vehicle having a chassis,

(a) a boom assembly movable'between a loaded, lifted and inoperative position in which it is lifted and folded back over said chassis and an unloaded, lowcred and operative position,

(b) a support assembly mounted upon the rear end of said chassis for swinging movement about a horizont-al axis extending transversely of said chassis,

(e) actuating means connected to said chassis and to said support means for vertically tilting the latter about said horizontal axis,

(d) a turntable pivotally mounted upon said support means for turning about a vertical axis,

(c) said boom assembly being mounted upon and carried by said turntable,

(f) a hydraulically operated lock means for maintaining said turn-table fixed against rotation about said vertical axis with said boom assembly disposed in longitudinal alinement with said chassis,

(g) a source of hydraulic fluid under pressure,

(h) a reversible control valve movable selectively to boom loading and unloading positions and connecting said sounce to said actuating means for operation of the latter,

(i) a selector valve interposed between said conduit valve and said actuating means,

(j) means connected to said selector valve and said lock means and preventing the application of fluid pressure from said source to said actuating means except when said lock means is locked to said turntable. v

5. The combination of claim 4 wherein said l-ookmeans comprises a lock pin engageable in a locking aperture in a turntable, a hydraulic cylinder having a piston carrying said lock pin, said connected means including a pivotal lever having one end connected to said piston and its other end connected to said selector valve.

6. In combination with a supporting frame, a power perated implement, means ope-ratively mounting said implement on the fame for movement about a positioning axis, selectively control-led means connected to said mounting means for displacing said implement through a predetermined st roke between an operative and an inoperative posit-ion, lock means rendered operative by the selectively controlled mean-s when the implement is in an aligned position on the mounting means for locking the implement against movement about said positioning axis, means connected to the selectively controlled means for preventing displacement of the implement to the inoperat-ive position until the implement is locked in said aligned position by the lock means, and release means responsive to completion of said predetermined stroke for releasing said lock means in the operative position of the implement to permit movement thereof about the positioning axis.

7. The combination of claim 6 wherein said means for preventing displacement of the implement comprises, relay valve means disp-laceable between positions establishing and blocking fluid communication with said selectively controlled means, and valve actuating means engageable by the lock means for displacement of the valve means to the fllllid establishing position when the implement is locked against movement about the positioning axis, said selectively controlled means including a fluid operated piston device, a source of fluid under pressure and a selector valve connecting said source to the piston device through the valve means in said position thereof establishing fluid communication, said lock means including piston means engageable with said valve actuating means and in fluid communication with said source through the selector valve and the release means, and a lock plunger connected to the piston means.

8. The combination of claim 7 wherein said release means comprises, a one-way check valve connecting said selectively controlled means to the lock means for exhausting fluid from the lock means when rendered operative, and pressure responsive valve means connecting said selectively controlled means to the look means for release thereof.

9. The combination of claim 6 wherein said release means comprises, a one-way check valve connecting said selectively controlled means to the lock means for exhausting fluid from the lock means when rendered ope-rative, and pressure responsive valve means connecting said selectively controlled means to the lock means for release thereof.

10. The combination of claim 7 wherein said valve actuating means comprises an over-center, trip-action element.

References Cited by the Examiner UNITED STATES PATENTS 2,365,773 12/ 19-44 Osgood 214-132 2,591,201 4/1952 Rowand 91-189 2,603,368 7/1952 Vance 214-673 X 2,607,197 8/1952 Johnson 91-189 2,740,214 4/1956 Collins 172-447 X 2,870,924 1/1959 Wills 214-138 2,897,986 8/1959 Davis 214-131 3,027,723 4/1962 Lewis 91-189 3,132,753 5/1964 Chaser et al. 214-16.42 3,134,492 5/1964 Parsen 214-138 HUGO O. SOHULZ, Primary Examiner.

GERALD M. FORLENZA, Examiner.

A. GRANT, Assistant Examiner. 

1. A FOLDABLE POWER OPERATED BOOM CONSTRUCTION COMPRISING IN COMBINATION A VEHICLE HAVING A CHASSIS, (A) A BOOM ASSEMBLY MOVABLE BETWEEN A LOADED, LIFTED AND INOPERATIVE POSITION IN WHICH IT IS LIFTED AND FOLDED BACK OVER SAID CHASSIS AND AN UNLOADED, LOWERED AND OPERATIVE POSITION, (B) A SUPPORT ASSEMBLY MOUNTED UPON THE REAR END OF SAID CHASSIS FOR SWINGING MOVEMENT ABOUT A HORIZONTAL AXIS EXTENDING TRANSVERSELY OF SAID CHASSIS, (C) ACTUATING MEANS CONNECTED TO SAID CHASSIS AND TO SAID SUPPORT ASSEMBLY FOR VERTICALLY TILTING THE LATTER ABOUT SAID HORIZONTAL AXIS, (D) A TURNTABLE PIVOTALLY MOUNTED UPON SAID SUPPORT MEANS FOR TURNING ABOUT A VERTICAL AXIS, (E) SAID BOOM ASSEMBLY BEING MOUNTED UPON AND CARRIED BY SAID TURNTABLE, (F) A HYDRAULICALLY OPERATED LOCK MEANS FOR MAINTAINING SAID TURNTABLE FIXED AGAINST ROTATION ABOUT SAID VERTICAL AXIS WITH SAID BOOM ASSEMBLY DISPOSED IN LONGITUDINAL ALINEMENT WITH SAID CHASSIS, (G) A SOURCE OF HYDRAULIC FLUID UNDER PRESSURE, (H) A CONTROL VALVE CONNECTING SAID SOURCE TO SAID TURNTABLE LOCK MEANS, (I) MEANS OPERABLE ONLY WHEN SAID LOCK MEANS IS LOCKING SAID TURNTABLE FOR CONNECTING SAID SOURCE TO SAID ACTUATING MEANS AND TO SELECTIVELY EFFECT RAISING AND LOWERING OF SAID SUPPORT MEANS, TURNTABLE AND BOOM ASSEMBLY. 